Update to the API docs

Created by: Xylakant

The API docs state that the API version is equal to the gitlab major version number, which is a of gitlab 4.1 a false assertion.

doc/api/README.md

@@ -10,7 +10,7 @@ If no, or an invalid, `private_token` is provided then an error message will be
 }
 ```
-API requests should be prefixed with `api` and the API version. The API version is equal to the GitLab major version number, which is defined in `lib/api.rb`.
+API requests should be prefixed with `api` and the API version. The API version is defined in `lib/api.rb`.
 Example of a valid API request: